This invention relates to optical devices and, more particularly, to the precise mechanical positioning of mechanical devices in an optical assembly.
Optical assemblies typically include mirrors, lenses, and/or other optical elements that produce, utilize, modify, and direct light rays. The light rays are often employed in precisely defined beams. It is therefore necessary that the optical elements be precisely positioned relative to each other. Positions, including both angular orientations in space and lateral positioning, must be precisely established and maintained to within very fine physical tolerances in order to properly align the optical device.
In a laboratory setting, it is usually possible to use optical mounts with mechanical adjustments that provide the precise positioning within the desired tolerances. In a production optical device, however, such laboratory mounts may be far too bulky and heavy. The optical elements are therefore mounted in supports that are machined to precise dimensions and tolerances. In many cases, the required extremely high tolerances push the limits of available machining technology. Consequently, the cost of such supports that require high precision, and the resulting optical devices, tends to be high. In order to maintain costs within desired limits, it is sometimes necessary to compromise the optical performance of the optical device.
There is a need for an improved approach to the adjustable support of optical elements within optical devices that is useful for production optical devices and also has an acceptable cost. The present invention fulfills this need, and further provides related advantages.
The present invention provides a method and structure to achieve the precise positioning of an optical device. The approach allows the optical device to be approximately positioned, and then the position is fine tuned by a non-force-applying approach to achieve precise optical alignment of the optical device. The positioning may be of any required type, either angular, displacement, or a combination thereof. No substantial weight or bulk are added to the structure by the use of the present approach. The present approach is readily applied in a mass-production environment with acceptable costs. The precise optical alignment is stably retained during service.
In accordance with the invention, a method for positioning an optical device comprises the steps of providing an optical device, providing a support comprising a support material which is capable of controllable and permanent mechanical deformation by a non-force-applying agent, and mounting the optical device to the support in a first position. The method further includes controllably and permanently locally deforming the support by the non-force-applying agent to reposition the optical device to a second position. The deforming is desirably accomplished by local heating, as with a laser heating pulse.
The support material is preferably a metal such as a shape memory alloy. It may be another type of metal that exhibits a phase transformation at a transformation temperature which produces a volume or shape change. The support material may also be a material having a residual stress therein which may be altered. Composite materials may also be used. The support material may also be a material that is mechanically deformed and/or otherwise altered by an applied magnetic field.
The optical device may have one, two, or more than two optical elements. Where there is more than one optical element, the step of controllably and permanently locally deforming includes the step of repositioning the optical elements relative to each other.
The step of controllably and permanently locally deforming may be accomplished in several stages. Thus, for example, the step may include first controllably deforming the support, and thereafter second controllably deforming the support to a final permanently deformed state. The success of the first controllable deformation is assessed, and then the second controllable deformation is performed as needed.
The present approach is based on the selection of the deformable support material to constitute at least a part of the support. The deformable support material may form the entire support, or only a part of the support. A separate positioning and adjustment structure is therefore not needed, so that no substantial weight or bulk is added to the optical device structure.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.